<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>选项卡作业</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }

        ul,
        ol,
        li {
            list-style: none;
        }

        .box {
            width: 600px;
            height: 400px;
            border: 3px solid pink;
            margin: 50px auto;
            display: flex;
            flex-direction: column;
        }

        .box>ul {
            height: 60px;
            display: flex;
        }

        .box>ul>li {
            flex: 1;
            background-color: skyblue;
            color: #fff;
            font-size: 20px;
            display: flex;
            justify-content: center;
            align-items: center;
            cursor: pointer;
        }

        .box>ul>li.active {
            background-color: orange;
        }

        .box>ol {
            flex: 1;
            position: relative;
        }

        .box>ol>li {
            width: 100%;
            height: 100%;
            background-color: purple;
            position: absolute;
            left: 0;
            top: 0;
            font-size: 100px;

            display: none;
        }

        .box>ol>li.active {
            display: block;
        }
    </style>
</head>

<body>
    <div class="box">
        <ul>
            <li class="active">a</li>
            <li>b</li>
            <li>c</li>
            <li>d</li>
        </ul>
        <ol>
            <li class="active">1</li>
            <li>2</li>
            <li>3</li>
            <li>4</li>
        </ol>
    </div>
    <script>
        var ulis = [...document.querySelectorAll("ul li")];
        var olis = [...document.querySelectorAll("ol li")];
        console.log(ulis);
        for (var i = 0; i < ulis.length; i++) {
            ulis[i].index = i;
            // console.log(ulis[i].index);
            ulis[i].addEventListener("click", function () {
                console.log(this.index);
                ulis.forEach(function (uli) {
                    uli.classList.remove("active");
                });
                olis.forEach(function (oli) {
                    oli.classList.remove("active");
                });
                this.classList.add("active");
                olis[this.index].classList.add("active");
            });
        }
    </script>
</body>

</html>